Fungi | Article about Fungi by The Free Dictionary Fungi | Article about Fungi by The Free Dictionary Related to Fungi: Fungi kingdom Fungi (fŭn`jī), kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites parasite, plant or animal that at some stage of its existence obtains its nourishment from another living organism called the host. Parasites may or may not harm the host, but they never benefit it. ..... Click the link for more information. , symbionts, or saprobes (see saprophyte saprophyte , any plant that depends on dead plant or animal tissue for a source of nutrition and metabolic energy, e.g., most fungi (molds) and a few flowering plants, such as Indian pipe and some orchids. ..... Click the link for more information. ). Previously classified in the plant kingdom, fungi are nonmotile, like plants, but lack the vascular tissues (phloem and xylem) that form the true roots, stems, and leaves of plants.

Most coenocytic (multinucleated) or multicelluar fungi are composed of multiple filaments, called hyphae, grouped together into a discrete organism called a mycelium. The cell walls of most fungi are of chitin compounds instead of cellulose; a group fungi known as cryptomycota lack chitinous cell walls. In many ways fungi are more closely related to animals than to plants, and they have been thought to share a common protist ancestor with animals. A recent classification system suggested by nucleic acid (genetic material) comparisons places the fungi with the animals and the plants in an overarching taxonomic group called the eukarya. Most fungi are capable of asexual and sexual reproduction reproduction, capacity of all living systems to give rise to new systems similar to themselves. The term reproduction may refer to this power of self-duplication of a single cell or a multicellular animal or plant organism. ..... Click the link for more information. .

Asexual reproduction is by fragmentation or spore spore, term applied both to a resistant or resting stage occurring among various unicellular organisms (especially bacteria) and to an asexual reproductive cell produced by many unicellular plants and animals and by all plants that undergo an alternation of generations. ..... Click the link for more information. formation. Those that reproduce sexually produce gametes in specialized areas of the hyphae called gametangia. The gametes may be released to fuse into spores elsewhere, or the gametangia themselves may fuse. In some cases dikaryons [di = two, karyo = nucleus], which are found only among fungi, result when unspecialized hyphae fuse but their nuclei remain distinct for part of the life cycle. Unlike algae or plants, fungi lack the chlorophyll necessary for photosynthesis and must therefore live as parasites or saprobes (see parasite parasite, plant or animal that at some stage of its existence obtains its nourishment from another living organism called the host. Parasites may or may not harm the host, but they never benefit it. ..... Click the link for more information. ).

Typically they release digestive enzymes onto a food source, partially dissolving it to make the necessary organic or inorganic nutrients available. Some parasitic types obtain their food directly from the cells of a living food source. Some types of fungi are involved in symbiotic relationships, for example, lichens lichen , usually slow-growing organism of simple structure, composed of fungi (see Fungi) and photosynthetic green algae or cyanobacteria living together in a symbiotic relationship and resulting in a structure that resembles neither constituent. ..... Click the link for more information. (a combination of a fungus and a green alga algae [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that lack true roots, stems, leaves, and flowers). ..... Click the link for more information. or a cyanobacterium cyanobacteria or blue-green algae, photosynthetic bacteria that contain chlorophyll. For many years they were classified in the plant kingdom along with algae, but discoveries made possible by the electron microscope and new biochemical techniques have shown them to be ..... Click the link for more information.

) and the mycorrhizae (symbiosis between a fungus and the roots of a vascular plant). Some fungi are pathogenic to humans and other animals. Such diseases are called mycoses or fungal infections fungal infection, infection caused by a fungus (see Fungi), some affecting animals, others plants. Fungal Infections of Human and Animals Many fungal infections, or mycoses, of humans and animals affect only the outer layers of skin, and although they are sometimes ..... Click the link for more information. . Some molds, in particular, release toxic chemicals called mycotoxins that can result in poisoning or death. Various fungi can also cause serious damage to fruit harvests and other crops (see diseases of plants diseases of plants. Most plant diseases are caused by fungi, bacteria, and viruses. Although the term disease is usually used only for the destruction of live plants, the action of dry rot and the rotting of harvested crops in storage or transport is similar to the rots ..... Click the link for more information. ).

Types of Fungi The 100,000 identified species of organisms commonly classed together as fungi are customarily divided into four phyla, or divisions: Zygomycota, Ascomycota, Basidiomycota, and Deuteromycota. Zygomycota includes black bread mold mold, name for certain multicellular organisms of the various classes of the kingdom Fungi, characteristically having bodies composed of a cottony mycelium. The colors of molds are caused by the spores, which are borne on the mycelium. ..... Click the link for more information. and molds, such as those of the genus Glomus, that form important symbiotic relationships with plants. Most are soil-living saprobes that feed on dead animal or plant remains. Some are parasitic of plants or insects. They reproduce sexually and form tough zygospores from the fusion of neighboring gametangia. There is no distinguishable male or female. Ascomycota includes yeasts yeast, name applied specifically to a certain group of microscopic fungi and to commercial products consisting of masses of dried yeast cells or of yeast mixed with a starchy material and pressed into yeast cakes. ..... Click the link for more information.

, the powdery mildews, the black and blue-green molds, edible types such as the morel and the truffle truffle [Fr.], subterranean edible fungus that forms a mutually beneficial (symbiotic) relationship with the roots of certain trees and plants. The part of the fungus used as food is the ascoma, the fruiting body of the fungus. ..... Click the link for more information. , and species that cause such diseases of plants diseases of plants. Most plant diseases are caused by fungi, bacteria, and viruses. Although the term disease is usually used only for the destruction of live plants, the action of dry rot and the rotting of harvested crops in storage or transport is similar to the rots ..... Click the link for more information. as Dutch elm disease, chestnut blight, apple scab, and ergot ergot , disease of rye and other cereals caused by the fungus Claviceps purpurea. The cottony, matlike body, or mycelium, of the fungus develops in the ovaries of the host plant; it eventually turns into a hard pink or purple body, the sclerotium, or ergot, that resembles ..... Click the link for more information. .

There are over 50,000 species, about 25,000 of which occur only in lichens. In ascomycetes, the hyphae are subdivided by porous walls through which the cytoplasm and the nuclei can pass. Their life cycle is a complex combination of sexual and asexual reproduction. Basidiomycota includes the gill fungi (most mushrooms mushroom, type of basidium fungus characterized by spore-bearing gills on the underside of the umbrella- or cone-shaped cap. The name toadstool is popularly reserved for inedible or poisonous mushrooms, but this classification has no scientific basis. ..... Click the link for more information. ), the pore fungi (e.g., the bracket fungi, which grow shelflike on trees, and an edible type called tuckahoe), and the puffballs puffball or smokeball, fungus in which the aboveground portion is typically a stemless brownish sac with an opening at the top through which issues the dustlike mass of ripe spores. The common puffball is Lycoperdon gemmatum. The giant puffball (L. ..... Click the link for more information. .

It also includes the fungi that cause smut smut, name for an order of parasitic fungi (Ustilaginales) and the various diseases of plants caused by them. Smuts produce sootlike masses of spores on the host. The spore masses may break up into a dustlike powder readily scattered by wind (loose smuts) or remain more or less ..... Click the link for more information. and rust rust, in botany, name for various parasitic fungi of the order Uredinales and for the diseases of plants that they cause. Rusts form reddish patches of spores on the host plant. About 7,000 species are known. ..... Click the link for more information. in plants. Like ascomycetes, the hyphae are subdivided by porous walls. In basidiomycetes, two hyphae fuse to form a dikaryotic mycelium (a mycelium in which both nuclei remain distinct). These mycelia differentiate into reproductive structures called basidia that make up the basidiocarp (the body popularly known as the mushroom cap). The nuclei then fuse and undergo meiosis, creating spores with one nucleus each.

When these spores germinate, they produce hyphae, and the process begins again. Deuteromycota comprises a miscellaneous assortment of fungi that do not not fit neatly in other divisions; they have in common an apparent lack of sexual reproductive features. Also called Fungi Imperfecti, the group includes species that help create Roquefort and Camembert cheeses, that cause diseases of plants and of animals (e.g., athlete's foot and ringworm ringworm or tinea , superficial eruption of the skin caused by a fungus, chiefly Microsporum, Trichophyton, or Epidermophyton. Any area of the skin may be affected, including the scalp and nails, but the most common site is the feet. ..... Click the link for more information. ), and that produce penicillin. A number of the fungi classified as deuteromycetes have been found to be asexual stages of species in other groups, and some classification schemes consider the deuteromycetes a class under Ascomycota.

Usefulness of Fungi Fungi are valuable economically as a source of antibiotics, of vitamins, and of various industrially important chemicals, such as alcohols, acetone, and enzymes, as well as for their role in fermentation processes, as in the production of alcoholic beverages, vinegar, cheese, and bread dough. They are extremely important in soil renewal, through the decomposition of organic matter (see humus humus , organic matter that has decayed to a relatively stable, amorphous state. It is an important biological constituent of fertile soil. Humus is formed by the decomposing action of soil microorganisms (e.g. ..... Click the link for more information. )—a function unwelcome when it results in the rotting of clothing and other goods and the spoilage of foods. Bibliography See C. M. Christensen, The Molds and Man (3d. rev. ed. 1965); J. Webster, Introduction to Fungi (1980); B. Kendrick, The Fifth Kingdom (1985); A. Chandra, Elsevier's Dictionary of Edible Mushrooms (1989); C. T. Ingold and H. J.

Hudson, The Biology of Fungi (6th ed. 1993); G. W. Hudler, Magical Mushrooms, Mischievous Molds (1998); P. Roberts and S. Evans, The Book of Fungi (2011). Fungi Nucleated, usually filamentous, sporebearing organisms devoid of chlorophyll; typically reproducing both sexually and asexually; living as parasites in plants, animals, or other fungi, or as saprobes on plant or animal remains, in aquatic, marine, terrestrial, or subaerial habitats. Yeasts, mildews, rusts, mushrooms, and truffles are examples of fungi. Some fungal classifications were constructed to facilitate identification, whereas others emphasize phylogeny. The more widely used classifications reflect a series of compromises between identification and phylogeny, and tend to conserve the vocabulary and nomenclature familiar to broad groups of users. The following is a conventional classification, in which all organisms are treated as members of the kingdom Fungi: Division: Eumycota Fungi – an introduction Fungi an introduction Fungi – an introduction After animals and plants, fungi are the third largest kingdom of eukaryotic organisms .

Most people see them as plants because they typically grow in soil and do not move around like animals in the search for food; supermarkets sell edible mushrooms such as white mushrooms and shiitake. But no fungi are capable of carrying out photosynthesis themselves; the fungal energy metabolism is driven by organic molecules of dead and sometimes also living organisms . Indeed, DNA comparisons have shown that fungi are more closely related to animals than to plants. According to these comparisons, the lineage that led to humans (and all other animals) separated from the lineage that led to truffles (and all other fungi) later than the lineage that gave rise to green plants. Mutation rate estimates (“molecular clock”) suggest that this happened about 800 million years ago in the Precambrian. Both the first fossil land plants and the earliest fossil fungi date back to around 400 million years ago. Although fungi are also found in oceans and fresh water, the majority of them live on the land, where they are virtually omnipresent and where they have tapped a huge variety of food sources. It is estimated that there are about 1.5 million different species of fungus, of which less than one tenth has been described scientifically.

A digestive organ turned inside out Fungi break down their food outside their bodies by excreting enzymes and they absorb nutrients in dissolved form through their cell membranes. This is similar to the food uptake method in the small intestine of human beings. The effective digestion and uptake of food needs an absorption surface that is as large as possible. In the intestines, this is achieved by so-called villi and the brush border of epithelial cell microvilli. A normal field mushroom can achieve a large absorption surface through a kilometre-long net of intertwined hyphae. The entirety of the thread-like hyphae is referred to as the mycelium. What is normally perceived as fungus is only a small part of the fungal organism, i.e. the fruiting body where the spores are formed. In contrast to animals and plants, fungi do not produce embryos, but instead they grow from tiny unicellular spores that are produced in huge quantities either sexually or asexually. With our every breath, we take up airborne fungal spores. Wood mushrooms (Lactarius spec.) © private For many people, fungi are less important than plants and animals in terms of the role they play.

However, due to their ability to convert organic dead matter into mineral resources, they play an important role in the global substance flow. They also constitute a much greater mass than the entire mass of animals, amounting to about one fourth of the earth's entire biomass. In a pine forest in Michigan, USA, a honey fungus (Armillaria bulbosa) was found whose mycelium, which originated from a single spore, covered an area of 37 ha and weighed around 11 t. The fact that this mycelium was indeed part of a single organism could be proven by the genetic analysis of samples taken at different sampling sites. False and true fungi Not all fungi form mycelia. Some fungi, yeasts for example, are unicellular organisms that reproduce asexually through cell division or budding, and grow as a diffuse mass. The transition from unicellular to multicellular organisms (and also the reverse) has happened repeatedly in the fungus kingdom. In the past, many different chlorophyll-free organisms that grew and subsisted like fungi were classified as fungi. In the meantime, molecular markers and genetic analysis in particular have led to a systematic that reflects natural relationships more correctly.

There is a general agreement that the so-called ray fungi (actinomycetes) are unrelated to fungi despite the fact that they have mycelia consisting of cell threads and form actinospores. Actinomycetes are prokaryotes (and hence nowadays called Actinobacteria). The best-known representative of actinomycetes, Streptomyces, is one of the most important antibiotics producers after Penicillium and related true fungi. What was previously classified as slime mould (including Dictyostelium and Physarum, popular model organisms for the development of unicellularity) is now no longer classified as fungus and instead is split into a separate heterogeneous group. Baker's yeast (Saccharomyces cerevisiae), a unicellular ascomycete © DKFZ The position of oomycetes is still a matter of controversy. Oomycetes comprise important plant pests such as Phytophthora infestans which leads to potato blight, or Plasmopara viticola, the downy mildew of grapevines.

In contrast to true fungi, the cell wall of oomycetes contains cellulose like that of green plants, and they form spores that can move around in water with flagella. The less well-known chytrids, which form mobile reproductive cells (asexual zoospores and sexually produced gametes), have a kind of intermediate position in that they can contain chitin and sometimes also cellulose. True fungi, however, do not contain cellulose but instead they have chitin as the major constituent of their cell wall. They do not have flagellar stages and sexual reproduction is not the result of the fusion of gametes, but rather of the conjugation of different hyphae. These hyphae are not referred to as female and male hyphae, but as minus and plus due to the lack of morphological differences. The conjugation of hyphae gives rise to the fungal fruiting body where spores are produced through meiosis. Zygomycetes or pin moulds are true fungi; a common example being black bread mould (Rhizopus stolonifer) or strawberry spoilage fungi.

The large group of "higher fungi" is divided into two groups, which differ in particular through their fruiting bodies in which the spores are formed: I. Ascomycetes or sac fungi: This is the largest fungal group, which includes popular edible mushrooms such as truffles and morels as well as many other species that can be both beneficial as well as harmful for humans, including Claviceps that grows on the ears of rye and other cereal plants (alkaloids), the moulds Aspergillus (aflatoxins, statins), Penicillium ( antibiotics ) and Tolypocladium (cyclosporin) as well as the yeast Saccharomyces used for making beer, wine, cakes and bread. Ascomycetes include a large number of specialist fungi, which are also able to break down the most resistant substances of the animal and plant kingdom, such as cellulose and lignin contained in wood, keratin contained in hair and nails and collagen contained in bones and connective tissue.

This fungal group is also of major importance for the industrial biotechnological production of enzymes and organic compounds such as citric acid or amino acids, not forgetting the fungi used for the maturation of cheeses such as Brie, Camembert, Gorgonzola or Vendôme. Mycorrhiza on cereal crops © University of Gießen II. Basidiomycetes or club-shaped mushrooms. This phylum includes the majority of edible and poisonous mushrooms as well as hallucinogenic mushrooms such as Psilocybe or Amanita, which are either extremely popular or extremely feared fungi, depending on the point of view. Some fungi of this phylum serve as the source of potent substances for the pharmaceutical and agricultural industries. The substance class of strobilurines, which is used for plant protection, was initially discovered in small Collybia fungi that grow on pine cones. Basidiomycetes also include dreaded plant pests such as rust or smut fungi. Numerous species form stable symbioses with the roots of trees and bushes (mycorrhiza), which is required by plants for their nutrient supplies from the soil. On the subject of fungi, lichens, which are associations of fungi and algae, also need to be mentioned.

They are possibly the most developed form of a symbiotic association and are of huge ecological importance as the primary settlers of inhospitable areas of the world. Many fungi do not reproduce sexually (or at least have not been observed to do so). Due to the lack of a fruiting body, they cannot be classified as ascomycetes or basidiomycetes. These fungi are therefore grouped as deuteromycetes or Fungi imperfecti (imperfect fungi). Medical importance of fungi Of the 150 or so known human pathogenic fungi, many are classified as Fungi imperfecti, including Candida albicans which is the major cause of genital infections in humans, and the causal agents of skin, hair and nail mycoses (dermatophytes). While these human pathogenic fungi are mainly experienced as unpleasant rather than dangerous, they can pose a great danger to people with a weakened immune system. Not only fungal infections, but also dead fungal cells or their components represent foreign antigens and can lead to allergies and represent a risk to human health. Fungal antigens are the most frequent allergens for humans. Poisoning does not just develop in its acute form, for example following the consumption of death caps.

About 2,500 mycotoxin-producing fungi are known, which is a higher number than fungi that can cause infections. There are known mycotoxins with organotoxic, mutagenic and teratogenic characteristics where little is so far known about their role in the development of liver cirrhosis, for example. Science still has a long way to go in fungal investigation. Glossary An antibiotic is a bacteriocidal or bacteriostatic substance produced by microorganisms (bacteria, fungi) of which minute concentrations inhibit the growth of bacteria. Antigens are foreign substances that stimulate the immune system to produce antibodies. Desoxyribonucleic acid (DNA) is a double-stranded, helical macromolecule encoding the genetic information of an organism. Eukaryotes are organisms whose cells have a nucleus and organelles. Eukaryotes include protozoa (unicellular organisms), algae, fungi, plants, and animals (including humans). A gene is a hereditary unit which has effects on the traits and thus on the phenotype of an organism. Part on the DNA which contains genetic information for the synthesis of a protein or functional RNA (e.g. tRNA).

Being lytic is the feature of a bacteriophage leading to the destruction (lysis) of the host cell upon infection. Mutations are any kind of alteration of genetic information (e.g., the exchange of a base; translocation of a DNA section; introduction of additional bases; loss of bases or entire DNA sections). Mutations occur constantly in nature (induced by UV rays, natural radioactivity) and are the basis of evolution. Mutagenesis means the production of mutations caused by, for example, UV light or other kind of radiation or numerous chemicals. There are two definitions for the term organism: a) Any biological unit which is capable of reproduction and which is autonomous, i.e. that is able to exist without foreign help (microorganisms, fungi, plants, animals including humans). b) Definition from the Gentechnikgesetz (German Genetic Engineering Law): “Any biological unit which is capable of reproducing or transferring genetic material.“ This definition also includes viruses and viroids. In consequence, any genetic engineering work involving these kinds of particles is regulated by the Genetic Engineering Law. Pathogenity is the ability to cause a disease.

One differentiates between human, animal, and plant pathogens which specifically cause a disease in either humans, animals or plants. Candida albicans is a yeast-like fungi, commonly found in the normal flora of the mouth, skin, intestinal tract, and vagina. Generally, candida is harmless, but can become clinically infectious in immune compromised people. Symbiosis in a biological context is the cohabiting of two or more diffrent species, which is benefiting for all of them. The toxicity is the poisonousness of a substance. Morphology is study of structure and form of the organisms. Heterogeneity means dissimilarity, diversity. Absorption means in a biological context: the absorption of a drug or of light Chitin is a polysaccharide, which is found in the exoskeleton of arthropods and in the cell walls of fungi. The molecule is composed of N-acetyl-D-glucosamine units, which are linked in the beta positions. Download and print functions The Kingdom Fungi The Kingdom Fungi How do fungi differ from plants? 1. Lack true tissues How do fungi differ from algae? 1. Lack chlorophyll 2.

Completely heterotrophic (saprophytic or parasitic or both) 1. Some can cause disease (example: ergot of rye, "St. Anthony's fire") or even death 2. Crop damage fungicide: a chemical substance used to kill or inhabit the growth of fungi How are fungi beneficial? 1. Provide leavening for breads [leavening: a substance which provides bubbles of gas in doughs or batters ("rise")] 2. Decompose organisms in the soil and damp areas (most important and most common) 3. Source of food (mushrooms and cheeses) 4. Medicines (penicillin) Alexander Fleming, 1929, First antibiotic Phylum Eumycophyta: true fungi; 47,000 species; (mushroom, mold, rust, yeast, smut); larger and more important Phylum Myxomycophyta: slime molds; 450 species The True Fungi Most fungi are multicellular and have a distinct threadlike structure or filaments, which form the body of a fungus (called hyphae). Yeasts are unicellular.

Septate: hyphae that has a wall separating the individual cells the wall is called the septum (septa plural) Nonseptate: hyphae that lack septa Hyphae serve different functions and are named accordingly: 1. Rhizoids: embedded in the material on which the fungus is growing; support the fungus and digests food 2. Aerial hyphae: not embedded in the material; absorb oxygen, produce spores, and spread the fungus 3. Stolons: aerial hyphae that produce new filaments 4. Sporophores: hyphae branches which produce spores 5. Haustoria: hyphae of parasitic fungi which enter the host's cells to obtain nutrition directly from the cytoplasm 6. Mycelia: masses of intertwined hyphae; forms the main body of a fungus mycologists: scientists who study fungi True fungi have cell walls composed of chitin: a hard substance also found in the exoskeletons of insects and crabs.

Most are colonial They lack specialized structures for digestion: external digestion Most common type of reproduction: Asexual Asexual reproduction: spores: most common asexual method fragmentation by stolons spores form: either within an enclosure (Sporangium: where spores are made); the whole structure is called a sporangiophore or not within an enclosure (Conidia: where spores are made); the whole structure is called a conidiophore Sexual reproduction: Hyphae (haploid) of two different mycelia come in contact, resulting in a diploid zygote. This forms a zygospore or forms a new mycelium which grows and becomes highly specialized fruiting body which produces and dispenses spores. perfect fungi: those which reproduce sexually imperfect fungi: those which do not reproduce sexually (1) Class Phycomycetes (a perfect fungus) contains many of the common molds Rhizopus nigricans: most common type of bread mold Its sporangium disperses tiny black spores Not all molds which grow on foods spoil the food; some actually make them more tasty.

For example, restaurants sometimes keep choice beefsteaks in a cooler where it is too cold for bacteria to grow but not too cold for a certain type of green mold to grow. The rhizoids of this mold grow slowly through the meat. The mold actually digests the meat for its own use. Later, when the green mold is scraped off and the meat is cooked, the steak is very tender and flavorful. Cheese molds: Cheese is formed by bacteria and molds. The bacteria help separate the solid, white curd from the watery whey of milk. After this separation is complete, mold spores are introduced into the curd and the molds are allowed to grow. The type of cheese that is formed depends on the kind of mold spores used, the rapidity with which the mold is allowed to grow, and the kind of milk curd used. Roquefort cheese is made from sheep's milk and a dark green type of mold; this famous French cheese was originally produced in cool caves where the mold grew very slowly. The pungent cheese known as Limburger is allowed to mold rapidly under warm and very humid conditions. Parasitic molds: cause serious problems for man because they feed on important foods.

Examples: late blight fungus of potatoes: the potato blight of 1845 caused the starvation of approx. 250,000 people in Ireland; also affects tomatoes: in 1946 the tomato crop in the eastern U.S. was cut by half (est.

loss of 50 million dollars) downy mildews: damages cabbage lettuce, cucumbers, spinach, beans, peas, and grapes Aquatic molds: often produce motile gametes; cause a cottony growth on dead fish (2) Class Ascomycetes (a perfect fungus) "sac fungi" sexually produce spores called ascospores inside a sac called an ascus asexually: conidia Examples: molds of the genus Penicillium antibiotic flavors of Roquefort (Penicillium roqueforti) and Camembert cheese red bread mold (Aspergillus & Neurospora) cause plant diseases (ergot of rye, chestnut blight, & the Dutch elm disease) powdery mildews (cobwebby mycelia on leaves & stems of lilacs, grapes, roses, apples, and squash) morel: delicately flavored; the cup fungi; form a saucer or bowl-shaped fruiting body yeasts: small, colorless, unicellular, saprophytic mostly (some parasites); feeds on foods containing sugar, converting the sugar into alcohol and C02 in the process.

yeasts reproduce asexually by budding (3) Class Basidiomycetes (a perfect fungus) "club fungi" produce spores in the club-shaped basidium; spores are called basidiospores most are saprophytes know its structure (gills, cap, stipe = fruiting body) Shelf fungi no gills - spores fall from holes on undersurface of fruiting body Rusts named for the rusty-colored spores that they leave on their hosts (such as wheat, oats, raspberries, melons, apple trees and evergreen trees); they are alternate parasites: means they must have two hosts in order to complete their life cycle (one is harmed and the other is not) Smuts produce masses of black spores on their hosts; attack grains (corn, oats, wheat, rye, barley); hyphae penetrate tissues of hosts and rob them of nourishment (can't grow); often destroy flowers so no grains are produced (4) Class Deuteromycetes (imperfect fungi) no sexual reproduction fan-shaped network of veinlike branches small group of unusual organisms - includes some yeasts normally found in moist habitats - sometimes on rotting logs, damp soil, and decaying organic material The L

ichens lichens: a group of dual organisms (composed of both fungi and algae).

The algae is surrounded by mycelium of the fungus, which provides the algae with a secure environment. Fungus provides the water and minerals; supports and protects the algae. The algae contains chlorophyll and is its food maker. Example of symbiosis: two different kinds of organisms living together mutualism: when both benefit and neither is harmed. 3 general categories of lichen (based on their appearance) 1) Crustose: crust-like; appear as flat or nearly flat smears of dried paint. 2) Foliose: leaf-like; small, crinkly leaves. 3) Fruticose: shrubby; have stalks or branches. Germs: Viruses, Bacteria, and Fungi Germs: Viruses, Bacteria, and Fungi Veterinary & Aquatic Services Department, Drs. Foster & Smith What is a germ? The term 'germ' actually refers to any microorganism , especially those microorganisms that cause disease. Included in this category are certain viruses, bacteria, and fungi. What is the difference between these three types of microbes? Which ones cause which diseases, and should they be treated differently?

Because viruses, bacteria, and fungi cause many well-known diseases, it is common to confuse them, but they are as different as a mouse and an elephant. A look at the size, structure, reproduction, hosts, and diseases caused by each will shed some light on the important differences between these germs. What is a virus? Viruses are very tiny, simple organisms. In fact, they are so tiny that they can only be seen with a special, very powerful microscope called an "electron microscope," and they are so simple that they are technically not even considered "alive." There are six characteristics of all living things: Adaptation to the environment Metabolic processes that obtain and use energy Movement response to the environment Growth and development Reproduction A virus is not able to metabolize , grow, or reproduce on its own, but must take over a host cell that provides these functions; therefore a virus is not considered "living." The structure of a virus is extremely simple and is not sufficient for an independent life. Structure: Each virus is made up of two elementary components. The first is a strand of genetic material, either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).

Unlike living cells, viruses will have either DNA or RNA, but not both. The genetic material is a blueprint for determining the structure and behavior of a cell. In a virus, a protein coat called a "capsid" surrounds the nucleic acid. This coat serves to protect the nucleic acid and aid in its transmission between host cells. The capsid is made of many small protein particles called "capsomeres," and can be formed in three general shapes – helical, icosahedral (a 20-sided figure with equilateral triangles on each side), and complex. Some of the more advanced viruses have a third structure that surrounds the capsid. This is called the "envelope" and is composed of a bilipid layer, like the membrane on a cell, and glycoproteins, which are protein and carbohydrate compounds. The envelope serves to disguise the virus to look like a 'real' cell, protecting it from appearing as a foreign substance to the immune system of the host. The structure of a virus is closely related to its mode of reproduction. Reproduction: A virus's sole purpose is to reproduce, but it needs a host cell to do so.

Once a suitable host cell has been located, the virus attaches to the surface of the cell or is ingested into the cell by a process called "phagocytosis." It then releases its genetic material into the cell, and essentially shuts down normal cell processes. The cell stops producing the proteins that it usually makes and uses the new blueprint provided by the virus to begin making viral proteins. The virus uses the cell's energy and materials to produce the nucleic acid and capsomeres to make numerous copies of the original virus. Once these 'clones' are assembled, the virus causes the host cell to rupture, releasing the viruses to infect neighboring cells. Viral Shapes Complex T-4 Bacteriophage Hosts and resistance: Viruses are known to infect almost any kind of host that has living cells. Animals, plants, fungi, and bacteria are all subject to viral infection. But viruses tend to be somewhat particular about what type of cells they infect. Plant viruses are not equipped to infect animal cells, for example, though a certain plant virus could infect a number of related plants. Sometimes, a virus may infect one creature and do no harm, but cause havoc when it gets into a different but closely related creature.

For example, deer mice carry the Hantavirus without much noticeable effect on the rodents, but if Hantavirus infects a person, it causes a dramatic, and frequently deadly, disease marked by excessive bleeding. Most animal viruses, however, are species specific. This means, they will infect one species of animal. For instance, feline immunodeficiency virus (FIV) will only infect cats; human immunodeficiency virus (HIV) will only infect humans. What does the host do in order to fight off the invasion of a virus? Any foreign substance introduced into the body produces what is called an "immune response." Through this process, the host's body produces antibodies. Antibodies are substances that will destroy an invader and prevent the host from contracting the same disease again in the future. Antibodies are specific to each invader, and each time that a new disease is contracted, a new set of antibodies will have to be manufactured. This process of making antibodies specific to the infecting virus takes about seven days. In the meantime, the cell infected with a virus produces small proteins called "interferons." These interferons are released within three to five days and function to prevent infection in neighboring cells until the antibodies can be made.

Needless to say, research on the benefit of interferons in viral treatment is underway, but the actual mechanism of an interferon is not entirely known. There are some antiviral medications that can be administered in the case of viral infection, but the body's immune system is largely relied upon to fight off these kinds of infections. What are bacteria? Bacteria are very different from viruses. First of all, bacteria are much larger in size. The largest virus is only as big as the very smallest bacterium (singular for bacteria). But bacteria are still microscopic and cannot be seen with the naked eye. They are so small that the sizes of bacteria are measured in micrometers (10,000 micrometers = 1 centimeter). By comparison, the head of a pin is about 1000 micrometers wide. Though more complex than a virus, the structure of a bacterium is still relatively simple. Structure: Most bacteria have an outer, rigid cell wall. This provides shape and support. Lining the inside of the cell wall is a plasma membrane. This is like the membrane found around all living cells that provides both a boundary for the contents of the cell and a barrier to substances entering and leaving.

The content inside the cell is called "cytoplasm." Suspended in the cytoplasm are ribosomes (for protein synthesis), the nucleoid (concentrated genetic material), and plasmids (small, circular pieces of DNA, some of which carry genes that control resistance to various drugs). All living cells have ribosomes, but those of bacteria are smaller than those found in any other cell. Some antibacterial medicines have been made that attack the ribosomes of a bacterium, leaving it unable to produce proteins, and therefore killing it. Because the ribosomes are different, the cells of the host are left unharmed by the antibiotic. Other antibiotics target certain portions of the cell wall. Some bacteria have long, whip-like structures called "flagella" that they use for movement. Bacteria can occur in three basic shapes: Coccus (spheres) Spirillum (spiral) Campylobacter jejuni Reproduction: Bacteria undergo a type of asexual reproduction known as "binary fission." This simply means they divide in two, and each new bacterium is a clone of the original – they each contain a copy of the same DNA. Bacteria can reproduce very quickly.

In fact, in an ideal laboratory situation, an entire population of bacteria can double in only twenty minutes. At this enormous growth rate, one bacterium could become a BILLION (1,000,000,000) bacteria in just 10 hours! Luckily, there are neither enough nutrients nor space available to support this rapid growth, or the world would be overrun with bacteria. As it is, bacteria can be found living on almost any surface and in almost any climate in the world. Hosts and resistance: As stated, bacteria can grow nearly everywhere. These microbes have been around for billions of years because they are able to adapt to the ever-changing environment. They can find a home anywhere, and some of them live in places where it was once thought 'nothing' could survive. There are bacteria in the soil, at the depths of the ocean, living in the mouth of volcanoes, on the surfaces of teeth, and in the digestive tracts of humans and animals. They are everywhere and are very numerous. For example, a single teaspoon of soil is said to contain at least 1,000,000,000 bacteria.

Most often, bacteria are thought of as a bad thing, but most bacteria are not pathogenic (disease-causing). In fact, many bacteria are very helpful to us. There are species that decompose trash, clean up oil spills, and even produce medicines. The few species that are pathogenic, however, give the rest of the bacteria a bad name. Pathogens are rated on two characteristics – invasiveness and toxigenicity. Invasiveness is a measure of the bacterium's ability to grow inside the host, and toxigenicity measures the capacity of the bacterium to produce toxins (chemical substances that cause damage to the host). The combination of these two characteristics gives the final rating of the bacteria's virulence (ability to cause disease). A species does not necessarily need to have both high invasiveness and high toxigenicity to be rated highly virulent. One or the other can be high enough to cause the bacterium to be very virulent. For example, the bacterium Streptococcus pneumoniae (causes pnuemonia) does not produce a toxin, but it is so highly invasive that it causes the lungs to fill up with fluid from the immune response.

In contrast, the bacteria Clostridium tetani (causes tetanus) is not very invasive, but it produces a potent toxin that causes damage at a very small concentration. How does the body fight off a bacterial infection? Again, the body mounts an immune response to the foreign invader, producing antibodies for immediate help and future protection. Since this process takes about a week, antibiotics are usually employed in the meantime. Antibiotic drugs are usually only successful in treating bacterial infections, not viral, or fungal infections. Professionals are becoming concerned that the overuse of antibiotics when they are not needed may lead to the mutation of normal bacteria into antibiotic-resistant bacteria. Bacteria are very resilient and have already developed resistance to many antibiotics. Another concern is that the helpful bacteria that live in the digestive tract may also fall prey to the antibiotics. These bacteria, known as "natural flora," produce vitamins that the host organism uses and needs, as well as help in the digestion of food. What is a fungus? Fungi (plural for fungus) are different from both viruses and bacteria in many ways. They are larger, plant-like organisms that lack chlorophyll (the substance that makes plants green and converts sunlight into energy).

Since fungi do not have chlorophyll to make food, they have to absorb food from whatever they are growing on. Fungi can be very helpful – brewing beer, making bread rise, decomposing trash – but they can also be harmful if they steal nutrients from another living organism. When most people think of fungi they picture the mushrooms that we eat. True, mushrooms are important fungi, but there are other forms such as molds and yeasts. Structure: The main identifying characteristic of fungi is the makeup of their cell walls. Many contain a nitrogenous substance known as "chitin," which is not found in the cell walls of plants, but can be found in the outer shells of some crabs and mollusks. Most fungi are multicellular (made up of many cells), with the exception of the yeasts. The cells make up a network of branching tubes known as "hyphae," and a mass of hyphae is called a "mycelium." The insides of the cells look a little different than bacterial cells.

First of all, the genetic material is gathered together and enclosed by a membrane in what is called the "nucleus." Also, there are other structures called "organelles" in the cell that help the cell to function, such as mitochondria (converts energy), endoplasmic reticulum (ER) (makes complex proteins), and other organelles. The Golgi apparatus forms many types of proteins and enzymes. Lysosomes contain enzymes and help digest nutrients. Centrioles are necessary for proper division of the cell. Both bacteria and fungi have ribosomes, but those of the bacteria are smaller in size and also reproduce differently. Reproduction: Fungi can reproduce in multiple ways depending upon the type of fungus and the environmental conditions: Budding

Question: Which substance contained by most other plants, do fungi lack?
Answer: CHLOROPHYLL